Telephone-exchange system.



G. BABCOCK.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED IAN-'22. 19l04 UNITED STATES PATENT OFFICE.

GARRTSON BAECOCK, OF ROCHESTER, NEW YORK, ASSIGNOR TO TELECHRONOMETERCOMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

' TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Application filed January 22, 1910. Serial No. 539,466.

telephone exchange systems, and has referenceparticularly to that classof service meters in which themetering mechanism is located at thesubstations.

It is an object of my invention to provide a service n etering system ofsucha kind that the operating magnet of the meter-is normallyshort-circuited by means of a shunt closed around its terminals eitherby the operated position of the meter or the normal position of thecontrolling mechanism connected with the line circuit, whichcontrollingmechanism is effective in causing the operation of the meter.

The controlling mechanism as shown in the present embodiment consistsessentially of a polarized relay adapted to be operated by a currentflowing in one direction in the line circuit, but unresponsive tocurrent flowing in the opposite direction. The meter operating"mechanism is so constructed that it E. 'iot normally in an operativeposition, and inust first be set before it can be operated to register acall.

The setting of the meter operating mechanism is accomplishedmechanically by the switch hook of the substation as it moves fremitsnormal to it's calling position. In

with the cord circuit used to establish con-- nection .between thecalling and the called lines. The operation of this relay serves tointerrupt a normal battery connection and connect to-the cord circuit asecond source of energy of higher potential than the batterynormallyemployed, which second source is connected to'the battery insuch a direction that when it supplies current to' the line such currentfiows in a direction through the battery in opposition to the directionof normal current-flow through .such

battery, and therefore is effective in charging the battery;-and it willbe understood that the difference of pressure between the two sources ofelectricity is impressed upon the line.

In the accompanying drawings illustrat ing my invention, the substationA is con- 'nected by line wires 1 and 2 with the exchange, the linecircuit there terminating in the tip and sleeve springs 3 and 4respectively of the line jack J. The springs 3 and 4 normally makecontact with the contact springs 5 and 6 respectively. The spring 5 isconnected with the Winding of the line relay 7 the other terminal ofwhich is connected by wire 8 with the negative pole of the battery B.The spring 6 is connected by wire 9 with the positive pole of battery B.

At the substation the line wire 1.is connccted by a wire 10-with thepivotal point of a polarized armature 11 of the combined induction coiland magnet 12, the core 13 of which is extended to attract the polarizedends of the armature 11. The armature 11 carries a contact 14 adaptedtoengage a contact 15' when the armature is in its normal position. Thecontact 15' is connected by a wire 16 with a contact 17 adapted toengage a spring 18 when the switch hook 19 is'in its raised or callingposition. The spring 18 is connected by a wire 20 with the primarywinding of the induction coil 12, the other terminal of which isconnected by wire 21 with the transmitter T, the other terminal of whichis connected directly to the line wire 2. The secondary winding of theinduction coil 12 is connected directly with the receiver R. asindicated.

The register mechanism 22 is adapted to be operated by a lever 23pivoted at 24 by, means of a pawl 25 pivoted at 26 to such hinge, asindicated at 28, said switch book being pivotally sunnm' ""1 The pawlPatented May 4, 1915.

27 is so conformed that -when the switch hook is in its lower or normalposition the shoulder formed on the lower end of such pawl rests overthe right-hand end of the lever 23, and as the switch hook 19 is raisedwhile being moved to its normal position the spring usually provided tocause this operation, and not shown, depresses the right-hand end of thelever 23, thus raising the pawl 25 to bring it into engagement with oneof the teeth of the register mechanism 22 in advance of the onepreviously engaged by such pawl.

The continued motion of the switch hook 19 in an upward direction causesengagement between a cam surface 27 a at its lower end and a fixed stop30, as a result of which the pawl 27 is moved upon its pivot 28 to causeit to be disengaged from the lever 23, which would thereupon fall to itsnormal position were it not for the new engagement.

between the pawl 25 and the register mech anism 22 above referred to.The lever 23 also serves asa polarized armature for the operating magnet31 of the registering mechanism, as a result of which when the magnet 31is properly energized the lever 23 is moved forcibly downward, thusrotatingthe registering mechanism to advance .it one in dication. Thismotion of the. lever23 depresses the spring 32 against the contactspring 33. The operating magnet 31 is connected between the line wire 1and the wire 16, as indicated, and the contact springs 32 and 33 areconnected to the terminals of the operating magnet, as result of whichwhen the lever 23 has been moved downward to its operated position theclosure of the contacts 32 and 33 establishes a short circuit betweenthe terminals of the operating magnet, and further operation of suchmagnet is therefore prevented until the lever 23 is again moved upwardmechanically by means of the switch hook 19. A further resultaccomplished by the closure of the con-- tacts 32 and 33 is that theimpedance of the operating magnet 31 is removed from the line circuitduring talking.

' The switch hook 19 is so disposed relatively to the contacts 17. and18- that when in its depressed position, which is its normal positionunder the weight of the receiver R, it engages a block of insulation 18carried by the spring 18, and thus separates the contacts 17 and 18 andinterrupts the circuit through the primary winding of the induction coil12, which. primary winding is also efl'ective in energizing the core 13to cause operation of the armature 11. The primary winding referred tois so wound that cur.- rent in one direction, which, in the embodimentherein shown, is assumed tobe in a direction entering the winding fromthe wire 21, will attract the armature 11 in a manner to close andmaintain such armature in its normal position to-close the contacts 14and 15, which closure establishes a shunt or short circuit through thewires 10 and 16 between the terminals of the operating magnet 31.

Assuming that the receiver. R has been removed from the switch hook 19,as shown at the substation A, the contacts 17 and 18 are closed, andthus in a manner well known in the art, the line relay 7 is energized bythe pulling up of its armature 34 against the contact 35, and a circuitis closed between the wires '8 and 9 through the line lamp 36 to signalthe operator at the ex change that a connection is desired. The currentin the line at this time flows through the transmitter T, the primarywinding of the induction coil 12 and through wires 16 andg10, and by themotion of the switch book 19 toits raised position the lever 23 and pawl25 have been set in a position to operate the register mechanism 22.This condition continues until the direction of current flow through theinstrumentalities v referred to is reversed, at which time the oppositepole-of the armature 11 is attracted, thus separating the contacts 14and 15, as a result of which the line current now flows through theoperating magnet 31 as well as through the other instrumentalities ,de-.scribed. This results in the attraction of the lever 23 and the advanceof the registering mechanism 22. When the lever 23 reaches its lowerposition it closes, the contacts 32 and 33, thus short-circuiting theoperating magnet 31, and the lever remains in this position, as a resultof its weight until again returned to its set position by the motion ofthe switch hook 19. The reversal of current flow in the line circuit isaccom plished as follows:

The cord circuit herein shown consists of two strands 37,- 38,-extendingfrom the tip and sleeve 39, 40 of the answering plug P to the tip andsleeve 41 and 42 of the calling plug P, respectively. The strands 37 and38 have. connected in them the listening key 43 and the ringing key 44,and these strands are interrupted conductively, although continuousinductively by the condensers 45, 46, in a manner well known in the art.An operators set 47 is provided in the usual manner, such set beingconnected with the listening key 43.

The battery B has its negativeterininal connected by the wires 8 and 48with one terminal of the winding of the tip supervisory relay 49, theother terminal of which is connected by wire 50 with the answering endof the strand 37. The same terminal of the battery. B is also connectedby wire 51 with one terminal of the winding of the tip supervisory relay52, the other terminal of which is connected with the calling end of thestrand 37 by wire 53. The positive pole of the battery B is connected bywire 54 with one terminal of the winding of the sleeve supervisory relay55, the other terminal of which is connected by wire 56 with the callingrild of the strand 38. The same pole of the battery B is also connectedby wires 54 and 57 with the back contact 58 of the armature 59 of therelay 55. The armature 59 is connected by wire 60 with one terminal ofthe winding of the sleeve supervisory relay 61, the other terminal ofwhich is connected by the wire 62 with the answering end of the sleevestrand 38. A generator'G is provided, and has its field winding 63connected by wires 64 and 65 directly with the terminals of the batteryB. The positive and negative brushes 66 and 67 of the generator areconnected respectively by wires 68 and 69 with the positive pole of thebattery B and the front contact 70 of the armature 59.

The armatures 71 and 72 of the supervisory relays 49 and 52 are normallyin engagement with their back contacts 73 and 74, which are connectedwith the super visory lamps 75 and 76, respectively, the

other terminals of these lamps being con nected together by the wire 9to the positive pole of the battery B. The armatures 71 and '72 areconnected together by the wire 77, and are also connected by the wire 78with the spring contact 79 of the plug seat switch S, the other member80 of which is connected by wire 81 with the negative pole of thebattery B.

As aresult of the circuit connections above described, when the operatoranswers a call received by the flashing of the lamp 36 and inserts theanswering plug P into the jack J the line relay 7 is deenergized by theseparation of the jaz-lr. springs? and 4 from the contacts 5 and 6,respectively, and cur rent is now supplied from the battery B throughthe supervisory windings 61 and 19 to the line wires 1 and 2 in the samedirection as it waspreviously supplied through the springs 5 and 6, as aresult of which no actuation of the armature 11 occurs, since the core13 is magnetized in the same di rection.

This condition continues until the called subscriber, after having beenproperly connected by the insertion of the calling plug P in the jack J,and o eration of the signaling mechanism, not s own, at the calledsubstation, responds by removing his receiver from his switchhook. Thesignaling mechanism at the substation is not shown here in detail sinceit forms no part of this invention. When the called subscriber removeshis receiver from the switch hook he closes a circuit through thesubstation apparatus, thus causing the energization of the relay 55.This results in pulling up the armature 59 and interrupting the. circuitfrom the positive pole of the battery B opposition to its voltage, andthe resultant voltageimpressed upon the strands 37 and. 38 is of aboutthe same valueas the voltage of the battery B but in a reversedirection. The generator G is especially constructed so as to supplydirect noiseless current to the substation circuit whichis adapted fortalking purposes, and by its flowthrough the primary winding of theinduction coil12 it reverses the polarity of the core 13, thus rotatingthe armature 11 around to the left upon its pivot 11 and separating thecontacts ,11 and 15, and, since the contacts 32 and 33 are open and thec0ntacts'17 and 18 are closed, the operating magnet 31' is energized,thus advancing the register 22, at the close of which operation thecontacts 32 and 33 are closed to prevent further accidentalregistration. Another registration can onl be made after the switch hook'19 has been moved to its'normal position and again"released.

From the circuits above described it will be noticed that thesupervisory lamps 75 and '7 6 are lighted when the apparatus at thecorresponding substations is rcturned to its normal position by hangingthe receivers upon the hooks and that flow of current through thesupervisory lamps 75 and 76 is interrupted by the opening of the plugseat S when the calling plug P is returned to its 7 normal position.

The lever 23 at the substation A is polarized in order that if thecontacts 14 and '15 becmne accidentally separated, the operating magnet'31 may not be actuated by an initial flow of current therethroughbefore the contacts 11 and 15 are closed by the energization of the core1 The polarization of the lever 23 is in such a direction that it" willonly respond to acurrent flow through the shown in connection with thesystem above described, is so arranged that no battery The potentialdeveloped by the generator &

- While I have shown my invention in the articular embodiment hereindescribed, I n

so not, however, limit myself to this construction, but desire to claimany equivalent that may suggest itself to those skilled in the art. a

,What I claim is:

1. In a telephone exchange system, the combination with amain exchange,telephone lines extending from substations to such exchange, a meter atone of such substations, comprising an operating electromagnet havinganarmature which is moved away from its magnet by the mechanical operationof the switch hook when the latter is released to close the line, asource of current at the exchange for supplying current for talkingpurposes to the line, application of such current to a calling lineinoperatively traversing the meter magnet, controlling mechanism for themeter included in the line circuit and inoperative to such current andmeans for reversing the direction of current flow to energize the metermagnet and actuate the meter by the attraction of its armature.

2. In a telephone exchange, the combination of amain exchange, telephonelines extending from substations to such exchange, a meter at one ofsuch substations, a battery at the exchange adapted to send signalingcurrent through a line when in calling condition, such current alsotraversing the meter controlling mechanism without effecting 1tsoperation, means for supplying talking current to the ialling linethrough the meter controlling mechanism without open ating the same, anda second source of current adapted to reverse the direction of currentflow and means actuated when the called subscriber responds to connectsuch second source of current into the line to reverse the direction ofcurrent flow in the line and to simultaneously charge such battery tooperate the meter.

3. In a telephone exchange system, the combination of a main exchange.telephone lines extending from substations to such exchange. a meter atone of such substations, two sources of current connected in opposition,means for connecting one of such two'sources of current connected inoppositlon, means for connecting one of such sources to a line inresponse to a call to supply signaling and talking current to the"linevwithout operating the meter controlling mechanism, and means operated bythe response of the called subscriber for connecting the second sourcethrough the first source to reverse the direction of current flow in theline to operate the meter.

5. In a telephone exchange system, the combination of a main exchange,telephone lines extending from substations to such exchange, a meter atone of such substations, a source of current at the exchange forsupplying signaling current to the lines, an operating electromagnet forthe meter, a controlling magnet having its coil connected to the linecircuit, a circuit for the operating magnet having contacts, an armaturefor the controlling magnet cooperating with said contacts and adapted byits operation to cause the energization of the operating magnet,application of signaling current to a calling line traversing thecontrolling magnet in an inoperative direction, and means for reversingthe direction of current flow through the line and the controllingmagnet to cause its operation, such operation of the controllingmagnetserving to cause current from the line to energize the operating magnetof the meter.

6i In a telephone exchange system, the combination of a main exchange,telephone lines extending from substations to such exchange, a meter atone of such substations, a source of current at the exchange forsupplying signaling current to the lines, an operating magnet for themeter adapted to be operated by current flowing over the line circuit. apolarized relay connected with the line circuit and adapted to beactuated by current flow through the line in but one direction, a shuntcircuit normally closed around the terminals of the operating magnet bysuch relay, means for supplying signaling current to such line inresponse to a call in an inoperative direction relatively to such relay,and means for reversing the direction of current flow in the line tooperate such relay, the operation of such relay serving to open theshunt circuit and cause actuation of the operating magnet.

7 In a telephone exchange system, the combination of a main exchange,telephone lines extending from substations to such crating magnet forthe meter adapted to be means operated by current flowing over the linecircuit, a polarized relay connected with the line circuit and adaptedto be actuated by current flow through the line in but one-direction, ashunt circuit normally. closed around the terminals of the operatingmagnet by such relay, means for supplying srgnaling current to such linein response to a call in an inoperative direction relatively to suchrelay, a second source of current of higher tpotential than the firstsource, and

the line circuit through and in opposition to the first source tooperate such relay, the operation of such relay serving to open theshunt circuit and close actuation of the op erating magnet.

In a telephone exchange system, the combination of a main exchange,telephone lines extending from substations to such exchange, a meter atone of such substations, a source of current at the exchange forsupplying signaling current to the lines, an operating magnet for themeter adapted to be operated by current flowing over the'line clrcuit, apolarized relay connected with the line circuit and adapted to beactuated by current flow through the line in butone direction, a shuntcircuit normally closed around the terminals of the operating magnet bysuch relay, means for supplying signaling current to such line inresponse to a call in an inoperative direction relatively to such relay,a second source of current of higher potential than the first source,and

means automatically operated by the response of the called subscriberfor connecting such second source to the line circuit through and inopposition to such first source to 'operate such relay, the operation ofsuch relay serving to open the shunt circuit and cause the actuation ofthe operating magnet. v

9. Ina telephone exchange system, the combination of a main exchange,telephone Jines. extending from substations to such exchange, a meter atone of such substations, a source of current at the exchange forsupplying current to such line in an lnoperative direction relatively tothe meter, a second source of current of higherpotential than thefirstsource, and means forconnecting such second source to the line throughand in opposltion to such first source to cause actuation of the meter.

,, ,a source of current at the exchange for supplying signaling currentto the lines, an opor connecting such' second source to switch hook ismoved from its normal to its Y calling position, such switch hookserving when in its normal position to' interrupt the circuit throughsuch relay, means for supplying signaling current to such line inresponse to a call in an inoperative direction relatively to such relay,and means for reversing the direction of current flow in the line tooperate such relay, the operation of such relay serving to open theshunt circuit and cause actuation of the operating magnet.

11. In a telephone exchange system, the combination of a main exchange,telephone lines extending from substations tosuch exchange, a meter atone of such substations, a source of current at the exchange forsupplying signaling current to the lines, an operating magnet for themeter adapted to be operated by current flowing over the line circuit, apolarized relay connected with the line circuit and adapted to beactuated by current fiow through the line in but one direction, a shuntcircuit normally closed around the terminals of the operating magnet bysuch relay, mechanism associated with the switch hook at the substationto set the shunt circuit and cause actuation of the operating magnet.

12. In a telephone exchange system, the combination of a main exchange,telephone lines extending from substations to such exchange, a meter atone of such substations, a source of current at the exchange forsupoperation of such'relay serving to open the plying signaling currentto the lines, an opf crating magnet for the meter adapted to be operatedby current flowing over the line circuit, a polarized'relay connectedwith the line circuit and adapted to be actuated by current flow throughthe line in but one direction, a shunt circuit normally closed aroundthe terminals of the operating magnet by such relay, means for'supplying sigmagnet adapted to be closed by the actuation of the meter.

13. In a telephone exchange system, the combination of a main exchange,telephone lines extending from substations to such exchange, a meter atone of such substations,

a source of current at the exchange for supplying signaling currenttothe lines, an operating magnet for the meter adapted to be operated bycurrent flowing over the line circuit, a polarized relay connected withthe line circuit and adapted to be actuated by current flow through theline in but one direction, a shunt circuit normally closed around theterminals of the operating magnet by such relay, mechanism associatedwith the switch hook at the substantion to set the meter actuatingmechanism when the switch hook is moved from its normal to its callingposition, such switch hook serving when in its normal position tointerrupt the circuit through such relay, means for supplying signalingcurrent to such line in response to a call-in an inoperative directionrelatively to such relay, a second source of current of higher potentialthan the first source, means for connecting such second source to theline circuit through and in opposition to the first source to operatesuch relay, the operation of such relay serving to open the shuntcircuit and cause actuation of the operating magnet, and a second shuntcircuit about the terminals of the operating magnet adapted to be closedby the actuation of the meter.

14. In a telephone exchange system, the combination of a main exchange,telephone lines extending from substations to such exchange, a meter at.one of such substations,

a source of current at the exchange for supplying signaling current tothe lincs,.an operating magnet for the meter adapted to be operated bycurrent flowing over the line circuit, a polarized relay connected withthe line circuit and adapted to be actuated by current flow through theline in but one direction, a shunt circuit normally closed around theterminals of the operating magnet by such relay, mcchanism associatedwith the switch hook at the. substation to set the meter actuatingmechanism when the switch hook is removed from its normal to its callingposition, such switch hook serv ing when in its normal position tointerrupt the circuit through such relay, means for supplying signalingcurrent to such line in response to a call in an inoperative directionto connect such second source to the line cir cuit through and inopposition to the first source to operate the polarized relay, theoperationof such polarized relay serving to open the shunt circuit andcause actuation of the operating magnet, and a second shunt circuitabout the terminals of the operating magnetadapted to be closed by theactuation of the meter.

15. In a central energy telephone system, a substation meter comprisingthe combination of registering mechanism having a movable actuatingmember, a normally open line circuit extending from the substation to anexchange, means for automatically setting the actuating membermechanically in closing the line circuit to call the exchange, and

means operated by the response of the called subscriber for actuatingthe member.

16, In a telephone system, a substation meter comprising the combinationbf registering mechanism, and an actuating member therefore, a linecircuit extending from the substation to an exchange, means forautomatically setting the actuating member mechanically in calling theexchange, and means operated by a reversal of current in the linecircuit resulting from the response of the called subscriber for movingthe actuating member.

17. In a central energy telephone system,

a substation metencomprising the combination of registering mechanism, anormally open line circuit having extending from the substation to anexchange, means ,for me chanically setting the meter'upon the dos ing ofthe circuit for talking purposes, and means electrically operatedby'responseof the called subscriber for actuating the meter.

18. In a telephone system, a substation meter comprising the-combinationof registering mechanism, a line circuit extending from the substationto an exchange, an operating magnet for the meter, and a controllingmagnet, such controlling magnct adapt-- ed to be operated by a reversalof current therethrough resulting from the response of the calledsubscriber. A

19. In a telephone system, a substation meter comprising the combinationof registering mechanism, an operating magnet for the meter, and acontrolling magnet, such operating magnet normally inoperative andadapted to be placed in operative condition by motion of the substationswitch hook to its calling position, such motion of. the switch hook toa calling position serving to mechanically set the meter.

21. In a telephone system, a substation meter comprising the combinationof registering mechanism, an operating magnet for the meter, and acontrolling magnet, such operating magnet normally rendered inoperativeby the controlling magnet and the substation switch hook and placed incondi tion to operate by motionof the switch hook to a calling positionand by operation of the controlling magnet, such motion of the switchhook to a calling position serving to mechanically set the meter.

22. In a telephone exchange system, the combination with a main exchangehaving an instrument circuit leading to a substation, and an inductivetype telephone set in said circuit comprising primary and secondarywindings, a polarized pole piece arranged in said windings and anarmature actuated thereby, of a service recording meter comprising apolarized electromagnet having its coil arranged in the instrumentcircuit, a branch circuit for shunting said meter magnets havingcontacts controlled by said armature, two sources for supplying currentto the instrument circuit in opposite directions and means oralternately connecting said sources to said circuit.

23. In a telephone exchange system, the combination with a main exchangehaving an instrument circuit leading to a substation, and an inductivetype telephone set in said circuitcomprising primary and secondarywindings, a pole piece magnetized by said windings and an armaturetherefor, said pole piece being polarized to attract its armature wheninfluenced by current flowing in one direction, of a service recordingmeter having an operating electromagnet arranged in the instrumentcircuit and polarized to respond to current flowing in the otherdirection, a shunt circuit for said magnet having contacts controlled bysaid armature, a source of current and means for alternating itsdirection of flow over the instrument circuit.

24. The combination with a telephone circuit, metering mechanismcomprising two polarized electromagnets arranged therein each controllinarmatures and a branch circuit for shunting the coil of one of saidmagnets having two sets of contacts each set being adapted to be closedby one of said armatures, of a source of current and means foralternating its direction flow to actuate one or the other of saidarmatures.

25. The combination with a telephone circuit carrying the ordinarytalking current and a pole changer for alternating the direc tion offlow of said current, of a metering apparatus comprising anelectromagnet polarized to respond to current of one pole, a shuntcircuit for short circuiting said mag-- not having contacts therein, asecond polarized electromagnet responding to current of the other poleand adapted to close said shunt circuit.

26. The combination with a telephone circuit carrying the ordinarytalking current and a pole changer for alternating the direction of flowof said current, of a metering apparatus comprising two electromagnets,arranged in the line circuit each polarized to respond to current of onepolarity only, a registering device actuated by one of the magnets andvmeans controlled by the other magnet for closing the line circuit aroundthe first mentioned magnet.

27. The combination with a telephone circuit carrying the ordinarytalking current and a pole changer, of two electromagnets comprisingcoils arranged in the line circuit, each magnet being polarized torespond to current of one polarity only, a registering device adapted tobe actuated by one of the magnets, a shunt circuit for the coil of saidmagnet controlled by the other magnet.

28. The combination with a telephone circuit carrying the ordinarytalking current and a pole charger, of two electromagnets comprisingcoils arranged in the line circuit, each magnet being polarized torespond to current of one polarity only, a registering device adapted tobe actuated by one of the magnets, a branch circuit leading from thetelephone circuit forming a shunt fa the coil of said magnet and havingcontacts therein controlled by the other magnet.

29. The combination with a telephone circuit comprising a telephoneinstrument set embodying a receiver hook, and a source of current, of aregistering mechanism, an electromagnet arranged in the telephonecircuit, an armature therefor for operating the register and operatingconnections between the receiver hook: and armature for setting thelatter in actuated position, a branch circuit leading from the telephonecircuit around the magnet and having normally open contacts adapted tobe closed upon the attraction of the armature.

30. The combination with a telephone circuit, the telephone set thereinembodying a movable member for opening and closing the circuit, of anclectromagnet comprising a coil connected in the circuit and an armatureoperated thereby, connections between the movable member and armaturefor setting the latter in actuating position when the former is adjustedto close the telephone circuit, a register adapted to be operated uponthe attraction of the armature, and a branch circuit leading around thecoil hav ing normally open contacts adaptedto be closed by the armature.

31. In a telephone system. embodying tele' phone subscribers circuitsand a central, office equipment comprising answering and calling cords,a, source of current connected to both cords and means for alternatingthe direction of tlow of said current over the answering cord, twooppositely polarized electroma-gnets arranged in each subscriberscircuit, a branch circuit leading from the latter for-shunting one ofsaid magnets and having two sets of normally open contacts therein onecontrolled by the magnet to be shunted, the second controlled by theother magnet, and a message metering device adapted to be actuated bysaid shunted magnet previous to its being short circuited.

32, In a telephone system, embodying a plurality of subscriberscircuits, a central .ofiice'- answering and calling cord circuits eachhaving the usual relays, apair'of normally open contacts in theanswering cord circuit adapted to be closed by the energizing of one ofthe relays of the calling cord circuit when a called circuit is closed,a source of current connected to said cord circuits and means foralternating the direction of flow of said current over a calling line,of metering apparatuses comprising registers, polarized electromagnetsfor operating them arranged in the subscribers circuits, branch circuitsleading from the latter 'around said magnets and having con tactstherein, other electromagnets polarized in opposition to the firstmentioned magnets also arranged in the subscribers circuits and adaptedto control the contacts of their respective branch circuits.

In a telephone subscribers circuit, the

combination with a metering apparatus comprising two oppositelypolarized electromagnets arranged in the telephone circuit and havingarmatures adapted to be attracted alternately upon the flow of currentin opposite directions through said magnets and branches leading fromthe telephone circuit forming shunts around one of said magnets, andhaving normally open contacts adapted to be closed by the operation ofthe armature of either magnet, of a registering mechanism adapted to beactuated by one of the armatures, means for manually setting it inretracted position, a source of current and means for alternating itsdirection of flow.

In Witness whereof, I hereunto subscribe my .name this 18th day ofJanuary, A. D.

GARRISON BABCOCK. Witnesses: I ALBERT C. BELL, ALBERT G. MGCALEB.

